Use of template function does not compile in c++1X

Question

// this compiles
mfunc<int, float> ok(some_func);

// this does not ???
mfunc<int, float>* no = make_mfunc(some_func);

Error C2672 'make_mfunc': no matching overloaded function found

Error C2784 'mfunc *make_mfunc(std::function &&)': could not deduce template argument for 'std::function &&' from 'void (int,float)'

Error C2784 'mfunc *make_mfunc(const std::function &)': could not deduce template argument for 'const std::function &' from 'void (int,float)'

// code
struct ifunc
{
};

template <typename ...Args>
struct mfunc : public ifunc
{
    using callback_type = std::function<void(Args...)>;

    mfunc(const std::function<void(Args...)>& func) : func(func) { }
    mfunc(std::function<void(Args...)>&& func) : func(std::move(func)) { }

    std::function<void(Args...)> func;
};

template <typename ...Args>
mfunc<Args...>* make_mfunc(const std::function<void(Args...)>& func)
{
    return new mfunc<Args...>(func);
}

template <typename ...Args>
mfunc<Args...>* make_mfunc(std::function<void(Args...)>&& func)
{
    return new mfunc<Args...>(std::move(func));
}

void some_func(int a, float b)
{
    printf("%d, %f", a, b);
}

The arg is just a function, how is the compiler to guess that you first want to turn this into a `std::function`? — Ulrich Eckhardt, May 10 '20 at 06:29
The compiler can't deduce `std::function` types from a function pointer parameter — Alan Birtles, May 10 '20 at 06:38
This is similar to: [link](https://stackoverflow.com/questions/9998402/c11-does-not-deduce-type-when-stdfunction-or-lambda-functions-are-involved) , but the template is variadic so that solution does not work for this case. — Alex Wennström, May 10 '20 at 07:28

Use of template function does not compile in c++1X

0 Answers0